WIP (Introduce WTF::NonNullPtr<T>.)

Source/core/dom/StyleSheetCollections.cpp

Index: Source/core/dom/StyleSheetCollections.cpp
diff --git a/Source/core/dom/StyleSheetCollections.cpp b/Source/core/dom/StyleSheetCollections.cpp
index 665c2402d636c54fe1cd7114a53b97b7512b7406..129f727e82dbb18f40650a322a522a5829e7cb3a 100644
--- a/Source/core/dom/StyleSheetCollections.cpp
+++ b/Source/core/dom/StyleSheetCollections.cpp
@@ -97,7 +97,7 @@ void StyleSheetCollections::insertTreeScopeInDocumentOrder(TreeScopeSet& treeSco
     do {
         --it;
         TreeScope* n = *it;
-        unsigned short position = n->comparePosition(*treeScope);
+        unsigned short position = n->comparePosition(treeScope);
         if (position & Node::DOCUMENT_POSITION_FOLLOWING) {
             treeScopes.insertBefore(followingTreeScope, treeScope);
             return;
@@ -108,23 +108,23 @@ void StyleSheetCollections::insertTreeScopeInDocumentOrder(TreeScopeSet& treeSco
     treeScopes.insertBefore(followingTreeScope, treeScope);
 }
 
-StyleSheetCollection* StyleSheetCollections::ensureStyleSheetCollectionFor(TreeScope& treeScope)
+StyleSheetCollection* StyleSheetCollections::ensureStyleSheetCollectionFor(NonNullPtr<TreeScope> treeScope)
 {
-    if (&treeScope == &m_document)
+    if (treeScope == &m_document)
         return &m_documentStyleSheetCollection;
 
-    HashMap<TreeScope*, OwnPtr<StyleSheetCollection> >::AddResult result = m_styleSheetCollectionMap.add(&treeScope, nullptr);
+    HashMap<TreeScope*, OwnPtr<StyleSheetCollection> >::AddResult result = m_styleSheetCollectionMap.add(treeScope.get(), nullptr);
     if (result.isNewEntry)
-        result.iterator->value = adoptPtr(new ShadowTreeStyleSheetCollection(toShadowRoot(treeScope)));
+        result.iterator->value = adoptPtr(new ShadowTreeStyleSheetCollection(*toShadowRoot(treeScope.get())));
     return result.iterator->value.get();
 }
 
-StyleSheetCollection* StyleSheetCollections::styleSheetCollectionFor(TreeScope& treeScope)
+StyleSheetCollection* StyleSheetCollections::styleSheetCollectionFor(NonNullPtr<TreeScope> treeScope)
 {
-    if (&treeScope == &m_document)
+    if (treeScope == &m_document)
         return &m_documentStyleSheetCollection;
 
-    HashMap<TreeScope*, OwnPtr<StyleSheetCollection> >::iterator it = m_styleSheetCollectionMap.find(&treeScope);
+    HashMap<TreeScope*, OwnPtr<StyleSheetCollection> >::iterator it = m_styleSheetCollectionMap.find(treeScope.get());
     if (it == m_styleSheetCollectionMap.end())
         return 0;
     return it->value.get();
@@ -279,11 +279,11 @@ void StyleSheetCollections::removePendingSheet(Node* styleSheetCandidateNode, Re
 
     m_pendingStylesheets--;
 
-    TreeScope* treeScope = isHTMLStyleElement(styleSheetCandidateNode) ? &styleSheetCandidateNode->treeScope() : &m_document;
+    NonNullPtr<TreeScope> treeScope = isHTMLStyleElement(styleSheetCandidateNode) ? styleSheetCandidateNode->treeScope() : &m_document;
     if (treeScope == &m_document)
         m_needsDocumentStyleSheetsUpdate = true;
     else
-        m_dirtyTreeScopes.add(treeScope);
+        m_dirtyTreeScopes.add(treeScope.get());
 
     if (m_pendingStylesheets)
         return;
@@ -303,37 +303,37 @@ void StyleSheetCollections::addStyleSheetCandidateNode(Node* node, bool createdB
     if (!node->inDocument())
         return;
 
-    TreeScope& treeScope = isHTMLStyleElement(node) ? node->treeScope() : m_document;
-    ASSERT(isHTMLStyleElement(node) || &treeScope == &m_document);
+    NonNullPtr<TreeScope> treeScope = isHTMLStyleElement(node) ? node->treeScope() : &m_document;
+    ASSERT(isHTMLStyleElement(node) || treeScope == &m_document);
 
     StyleSheetCollection* collection = ensureStyleSheetCollectionFor(treeScope);
     ASSERT(collection);
     collection->addStyleSheetCandidateNode(node, createdByParser);
 
-    if (&treeScope == &m_document) {
+    if (treeScope == &m_document) {
         m_needsDocumentStyleSheetsUpdate = true;
         return;
     }
 
-    insertTreeScopeInDocumentOrder(m_activeTreeScopes, &treeScope);
-    m_dirtyTreeScopes.add(&treeScope);
+    insertTreeScopeInDocumentOrder(m_activeTreeScopes, treeScope.get());
+    m_dirtyTreeScopes.add(treeScope.get());
 }
 
 void StyleSheetCollections::removeStyleSheetCandidateNode(Node* node, ContainerNode* scopingNode)
 {
-    TreeScope& treeScope = scopingNode ? scopingNode->treeScope() : m_document;
-    ASSERT(isHTMLStyleElement(node) || &treeScope == &m_document);
+    NonNullPtr<TreeScope> treeScope = scopingNode ? scopingNode->treeScope() : &m_document;
+    ASSERT(isHTMLStyleElement(node) || treeScope == &m_document);
 
     StyleSheetCollection* collection = styleSheetCollectionFor(treeScope);
     ASSERT(collection);
     collection->removeStyleSheetCandidateNode(node, scopingNode);
 
-    if (&treeScope == &m_document) {
+    if (treeScope == &m_document) {
         m_needsDocumentStyleSheetsUpdate = true;
         return;
     }
-    m_dirtyTreeScopes.add(&treeScope);
-    m_activeTreeScopes.remove(&treeScope);
+    m_dirtyTreeScopes.add(treeScope.get());
+    m_activeTreeScopes.remove(treeScope.get());
 }
 
 void StyleSheetCollections::modifiedStyleSheetCandidateNode(Node* node)
@@ -341,13 +341,13 @@ void StyleSheetCollections::modifiedStyleSheetCandidateNode(Node* node)
     if (!node->inDocument())
         return;
 
-    TreeScope& treeScope = isHTMLStyleElement(node) ? node->treeScope() : m_document;
-    ASSERT(isHTMLStyleElement(node) || &treeScope == &m_document);
-    if (&treeScope == &m_document) {
+    NonNullPtr<TreeScope> treeScope = isHTMLStyleElement(node) ? node->treeScope() : &m_document;
+    ASSERT(isHTMLStyleElement(node) || treeScope == &m_document);
+    if (treeScope == &m_document) {
         m_needsDocumentStyleSheetsUpdate = true;
         return;
     }
-    m_dirtyTreeScopes.add(&treeScope);
+    m_dirtyTreeScopes.add(treeScope.get());
 }
 
 bool StyleSheetCollections::shouldUpdateShadowTreeStyleSheetCollection(StyleResolverUpdateMode updateMode)
@@ -377,13 +377,13 @@ bool StyleSheetCollections::updateActiveStyleSheets(StyleResolverUpdateMode upda
         HashSet<TreeScope*> treeScopesRemoved;
 
         for (TreeScopeSet::iterator it = treeScopes.begin(); it != treeScopes.end(); ++it) {
-            TreeScope* treeScope = *it;
+            NonNullPtr<TreeScope> treeScope(*it);
             ASSERT(treeScope != &m_document);
-            ShadowTreeStyleSheetCollection* collection = static_cast<ShadowTreeStyleSheetCollection*>(styleSheetCollectionFor(*treeScope));
+            ShadowTreeStyleSheetCollection* collection = static_cast<ShadowTreeStyleSheetCollection*>(styleSheetCollectionFor(treeScope));
             ASSERT(collection);
             collection->updateActiveStyleSheets(this, updateMode);
             if (!collection->hasStyleSheetCandidateNodes())
-                treeScopesRemoved.add(treeScope);
+                treeScopesRemoved.add(treeScope.get());
         }
         if (!treeScopesRemoved.isEmpty())
             for (HashSet<TreeScope*>::iterator it = treeScopesRemoved.begin(); it != treeScopesRemoved.end(); ++it)